I used PROFIS Engineering to calculate the post-installed drill depth for lapping a new T16 bar to an existing T20 bar. The software provided two different embedment depths:
- 240 mm for the new T16 bar
- 300 mm for the existing T20 bar
I understand these values are likely governed by the minimum lap length requirement, typically 15 Γ bar diameter.
Can I adopt 240 mm as the minimum drill-in depth for the new T16 bar in this lap splice scenario?
Thank you for your enquiry regarding lap length requirements for post-installed rebar connections.
Please note that the calculation of our Post-Installed Rebar (PIR) solution is based on the provisions of EN 1992-1. According to this standard, the minimum lap length πβ,βα΅’β should satisfy the following condition:
πβ,βα΅’β β₯ max{0.3 Γ Ξ±β Γ πb,α΅£qd, 15 Γ π, 200 mm}
In lap splice scenarios involving rebars of different diameters, such as a new T16 bar connected to an existing T20 bar, EN 1992 does not provide an explicit clause addressing this configuration. However, it is generally a more conservative approach to use the larger bar diameter (in this case, T20) when calculating the lap length.
Itβs worth noting that certain provisions in the local code issued by HKBD may permit lap length calculations based on the smaller bar diameter in some specific cases. However, such allowances are not incorporated into the PROFIS Engineering software, which strictly follows the Eurocode design principles.
Please feel free to reach out if further clarification or assistance is needed.
Regards,
Ron Siu
Technical Engineer